Spatial and temporal variations of aridity shape dung beetle assemblages towards the Sahara desert

Assemblage responses to environmental gradients are key to understand the general principles behind the assembly and functioning of communities. The spatially and temporally uneven distribution of water availability in drylands creates strong aridity gradients. While the effects of spatial variations of aridity are relatively well known, the influence of the highly-unpredictable seasonal and inter-annual precipitations on dryland communities has been seldom addressed. Aims: Here, we study the seasonal and inter-annual responses of dung beetle. Dung beetle abundance and species richness showed large seasonal variations, but remained relatively similar between years. Indeed, aridity and its interaction with season and year were the strongest correlates of variations in species richness and composition. Increasing aridity resulted in decreasing species richness and an ordered replacement of species, namely the substitution of the Mediterranean fauna by desert assemblages dominated by saprophagous and generalist species both in space towards the Sahara and in the dry season.Indradatta deCastro-Arrazola was funded by an FPI grant from the Spanish Ministry of Science and Innovation (BES-2012-054353). This work was supported by the Spanish Ministry of Science and Innovation project SCARPO (grant CGL2011-29317)